Non-aqueous secondary batteries (hereinafter, also referred to simply as “secondary batteries”), such as lithium ion secondary batteries, have characteristics such as compact size, light weight, high energy density, and the ability to be repeatedly charged and discharged, and are used in a wide variety of applications. A secondary battery generally includes battery members such as a positive electrode, a negative electrode, and a separator that isolates the positive electrode and the negative electrode from one another and prevents short-circuiting between the positive and negative electrodes.
In recent years, battery members including a porous membrane layer with the aim of improving heat resistance and strength, an adhesive layer with the aim of improving adhesiveness between battery members, or the like have been used in secondary batteries.
Specifically, electrodes that further include an adhesive layer formed on an electrode substrate in which an electrode mixed material layer is provided on a current collector and separators that include an adhesive layer formed on a separator substrate have been used as battery members. An adhesive layer such as mentioned above is typically formed by supplying, onto a suitable substrate such as an electrode substrate or a separator substrate, a composition for a non-aqueous secondary battery adhesive layer (hereinafter, also referred to simply as a “composition for an adhesive layer”) that is in the form of a slurry containing a binder component and a dispersion medium such as water, and then drying the composition for an adhesive layer (for example, refer to PTL 1).
PTL 1 proposes a technique of improving electrical characteristics of a non-aqueous secondary battery by integrating an electrode substrate including an electrode mixed material layer and a separator substrate through adhesion by an adhesive layer to inhibit cell swelling and increased inter-electrode distance associated with repeated charging and discharging. PTL 1 attempts to achieve good battery characteristics through formation of an adhesive layer using a small amount of adhesive.